Since optical discs such as a CD (Compact Disc) and a CD-ROM (Compact Disc Read Only Memory) are easy to handle and are produced at relatively low cost, they have been widely used as recording mediums for storing data. In recent years, a CD-R (Compact Disc Recordable) disc, on which data can be recorded once, and a CD-RW (Compact Disc ReWritable) disc, on which data can be rewritten, have come out. Thus, data can be easily recorded on such recordable optical discs. As a result, optical discs that accord with the CD standard such as a CD-DA (Digital Audio) disc, a CD-ROM disc, a CD-R disc, and a CD-RW disc have become the mainstream of data recording mediums. In addition, in recent years, audio data is compressed according to the MP3 (MPEG1 Audio Layer-3) and the ATRAC (Adaptive TRansform Acoustic Coding) 3 and recorded on the CD-ROM disc, the CD-R disc, the CD-RW disc, and so forth.
However, as a CD-R disc and a CD-RW disc have come out, data recoded on a CD disc can be easily copied to those discs. As a result, a problem about copyright protection has arisen. Thus, when content data is recorded to a recordable optical disc, it is necessary to take measures to protect content data.
FIG. 12 shows an outline of a flow of a copying process. A reproducing apparatus denoted by reference numeral 41 reproduces data from an original disc, for example a CD 42. Reference numeral 43 represents an optical pickup. Reference numeral 44 represents a reproduction signal processing portion. Reproduced signal is supplied from the reproducing apparatus 41 to a recording process portion 52 of a recording portion 51. An optical pickup 53 records the reproduced data to an optical disc, for example a CD-R 54. The recorded contents of the original CD 42 are recorded to the CD-R 54. Using the reproducing apparatus 41 and the recording portion 51, a copied disc of the original CD 42 can be easily produced.
In the case of a CD, as shown in FIG. 13, a sync detecting portion 46 of the reproducing process portion 44 detects a frame sync from a reproduced signal supplied from an input terminal 45. An EFM demodulator 46 EFM-demodulates the reproduced signal and supplies the EFM-demodulated reproduced data to a CIRC (Cross Interleave Reed-Solomon Code) decoder 48. The CIRC decoder 48 corrects an error of the reproduced signal. The EFM converts each symbol (eight data bits) into 14-channel bits and adds merging bits of three bits between adjacent blocks of 14 channel bits. A sub code decoder 49 decodes the reproduced data and obtains a reproduced sub code.
FIG. 14 shows an outlined structure of a recording process portion 52. Data to be recorded is supplied from an input terminal 55 to a CIRC encoder 56. The CIRC encoder 56 performs a CIRC encoding process for the data supplied from the input terminal 55. In addition, a sub code is supplied from an input terminal 57 to a sub code encoder 58. The sub code encoder 58 formats the sub code. An output of the CIRC encoder 56 and an output of the sub code encoder 58 are supplied to a multiplexer 60. In addition, a frame sync is supplied from an input terminal 59 to the multiplexer 60. The multiplexer 60 arranges those data in a predetermined order. An output of the multiplexer 60 is supplied to an EFM modulator 61. The EFM modulator 61 performs an EFM modulating process for data that is output from the multiplexer 60.
As one method for protecting content data recorded on a CD disc, it is determined whether the loaded disc is an original CD or a copied CD thereof. When the loaded disc is an original CD, a copying operation thereof can be permitted. When the loaded disc is a copied disc, a further copying operation thereof can be prohibited.
To determine whether the loaded disc is an original disc or a copied disc, a method for inserting a defect onto a disc during a master disc production, detecting the defect from a disc during a reproduction, and determining whether the disc is an original disc depending on whether or not the defect has been detected has been proposed. In this method, however, an original disc may contain a defect. In addition, depending on the type of a defect, it can be copied as it is. As a result, content data of an original disc cannot be prevented from being copied to a CD-R.